Reducing the amount of energy consumption by a fluid-handling dishwasher is an ongoing effort in the industry, particularly in view of the increasing worldwide energy demand and associated environmental and economic concerns. Conventional dishwashers are typically connected only to a structure's hot water supply to take advantage of the high initial temperature of the influent supply. However, a building's hot water heater (or other source of hot water) is generally a high energy consumption device, and a majority of the energy consumed by conventional dishwashers is indirectly attributed to the hot water heater.
Efforts are being made to reduce the energy consumption profile of dishwashers. For example, U.S. Pat. No. 4,070,204 describes a low-energy dishwasher connected to both hot and cold water lines, wherein cold water is used for a pre-rinse and one or more post-rinse cycles. Hot water is used for a wash cycle and a final post-rinse cycle followed an air-circulated drying cycle. Drying time is reduced by the residual heat of the dishes from the hot water post-rinse cycle. U.S. Pat. No. 7,776,159 describes a closed-loop feedback system for more efficient use of the amount of water used by a dishwasher. Likewise, U.S. Pat. Application Pub. No. 2008/0023042 describes various methods for more efficient management of water consumption of a dishwasher.
The above systems and control methods, however, still rely on hot water from an outside source (typically a high energy consumption source) as the initial influent supply to the machine for each wash cycle and, thus, the dishwasher indirectly contributes to the energy consumption of such sources. Particularly for less efficient hot water systems, this contribution can be significant.
Accordingly, it would be desirable to provide a dishwasher (and associated method of control) that reduces the dishwasher's energy consumption placed on an external hot water supply system.